1. Field of the Invention
The present invention relates to a color liquid crystal display device using a color filter for displaying a plurality of colors, and in particular, to a color liquid crystal display device wherein the adhesion of an indium tin oxide (ITO) film formed on an organic overcoat film with which a color filter is coated is enhanced.
2. Description of the Related Art
FIG. 2 is a sectional view of a conventional color liquid crystal display device 63. A plurality of transparent strip electrodes 56a made of ITO are formed in parallel with each other on one surface of a substrate 51a which is one of a pair of light-transmitting substrates 51, 51a displaced in the color liquid crystal display device 63 and an orientation film 57a is formed thereon. A color filter 52 is formed on almost entirety of one surface of the substrate 51 in such a manner that red, green and blue stripe filters are arranged by turns or the three-colors rectangular filters are arranged in a mosaic pattern. Additionally, after an organic overcoat film 53 made of acrylic or polyimide resin is formed on the color filter 52 for smoothing a transparent electrode 56 made of ITO or the like is formed by using a method such as sputtering, and besides, an orientation film 57 is formed thereon.
A liquid crystal material 60 and a plastic spacer 68 are inserted into a portion sandwiched between the above-mentioned light-transmitting substrates 51, 51a and the portion is sealed with a sealing material 59. Polarizing plates 61, 61a are respectively arranged on the other surfaces of the light-transmitting substrates 51, 51a, which are not facing each other. A tape automated bonding (TAB) 62 in which a large scale integrated circuit 64 for driving is mounded is connected to a terminal portion 66b in the color liquid crystal display device 63.
Generally, in the color liquid crystal display device 63 using the color filter 52, it is particularly important to keep the smoothness of the surface of the color filter 52 in view of preventing nonuniformity of color or contrast. Therefore, a transparent electrode is formed by coating the ITO film 56 in a manner such as sputtering method after the surface of the color filter 52 is coated with the organic overcoat film 53 made of acyrlic or polyimide resin for smoothing.
Since the organic overcoated film 53 exists between the color film 52 and the ITO film 56 of the liquid crystal display device 63 produced in such a manner, formation of the ITO film 56 on the surface of the organic overcoat film is conducted at a temperature of about 250.degree. C. or below in an amibience of a mixture of argon and oxygen by using a manner such as sputtering. However, adhesion between the organic overcoat film 53 and the ITO film 56 significantly decreases, which is apt to cause a crack or peeling. This is because, for example, the surface of the organic overcoat film 53 deteriorates due to oxidation. Thus, there is a problem that the connection between the terminal portion 66b of the ITO film 56 and the TAB 62 mounting the LSI 64 for driving can not be secured.
It is an object of the invention to provide a color liquid crystal display device in which adhesion between an ITO film and an organic overcoat film can be improved.